Evidence of humans in South America 22,000 years ago MAR 31 2014

Researchers here say they have unearthed stone tools proving that humans reached what is now northeast Brazil as early as 22,000 years ago. Their discovery adds to the growing body of research upending a prevailing belief of 20th-century archaeology in the United States known as the Clovis model, which holds that people first arrived in the Americas from Asia about 13,000 years ago.

"If they're right, and there's a great possibility that they are, that will change everything we know about the settlement of the Americas," said Walter Neves, an evolutionary anthropologist at the University of Sao Paulo whose own analysis of an 11,000-year-old skull in Brazil implies that some ancient Americans resembled aboriginal Australians more than they did Asians.

Up and down the Americas, scholars say that the peopling of lands empty of humankind may have been far more complex than long believed. The radiocarbon dating of spear points found in the 1920s near Clovis, N.M., placed the arrival of big-game hunters across the Bering Strait about 13,000 years ago, long forming the basis of when humans were believed to have arrived in the Americas.

More recently, numerous findings have challenged that narrative. In Texas, archaeologists said in 2011 that they had found projectile points showing that hunter-gatherers had reached another site, known as Buttermilk Creek, as early as 15,500 years ago. Similarly, analysis of human DNA found at an Oregon cave determined that humans were there 14,000 years ago.